1. Field of the Invention
This invention relates to navigation information systems. It is particularly suitable for use in providing users of road vehicles with route guidance, but other applications are possible and are discussed below.
2. Related Art
Navigation of a vehicle through an unfamiliar complex road network is a difficult task. Large amounts of fuel and time are wasted as a result of drivers getting lost or using an inefficient route. Accidents can also be caused by drivers attempting so read maps or complex road signs and losing concentration on the road ahead. Moreover, a driver may choose an inefficient route as a result of using an out-of-date map.
An additional problem car occur even if a driver knows a route to his or her destination. That route may be congested or blocked as a result of accidents or maintenance work, so that an alternative route would be more efficient.
Several proposals have been made for navigation guidance systems. In some such proposals a vehicle-borne system has a navigation computer and a geographical information system which is essentially a digitised map stored on a CD-ROM. The system gives the driver information and guidance by screen and/or speech display. These systems would be very expensive. Each vehicle requires a navigation computer and geographical information system. The cost of the complex vehicle-borne equipment involved is estimated to be in the region of £1000. The system is complex to operate, and could only be safely operated by the driver whilst the vehicle is stationary. The geographical information system would require periodic updating, which requires new disks to be distributed to subscribers from time to time.
In some proposed systems of this type real-time data would be broadcast over a radio network to update fixed information held on the geographical information system. Even so, the geographical information system would only be accurate up to its last update. Moreover, a broadcast channel needs to be allocated for the updating service.
It has also been proposed that the guidance service provider collects statistical traffic flow data from which traffic congestion predictions can be made which are fed into the real-time data to be broadcast. The traffic flow data may be collected using roadside sensors, or they may be collected by monitoring the operation of the mobile user equipment. The latter approach can only collect data relating to users of the system, but has a lower capital cost.
In an alternative approach a system of short-range roadside beacons is used to transmit guidance information to passing vehicles equipped with simple transceivers. The beacons transmit information to suitably equipped passing vehicles to give turn instructions appropriate to their chosen destinations. For each beacon the territory to be covered is divided into as many zones as there are exits from the junction the beacon relates to. The zone in which the user""s chosen destination falls is determined, and instructions are given appropriate to that zone. At any given beacon all vehicles whose destinations are in the same zone get the same instruction. The definitions of the zones are dependant on the location of the beacons, and each zone comprises the set of destinations which should be reached from the beacon by taking the direction associated with that zone.
Each beacon only gives instructions for reaching the next beacon along the route to the vehicle""s destination. For two vehicles starting from the same point for different destinations for which the routes are initially coincident, the beacons along the coincident section of route will each give both users the same instructions, because for those beacons both users are travelling to the same zone. Only for the beacon at the point of divergence are the two users"" destinations in different zones, and therefore different instructions are given.
The beacons"" programming may be modified from time to time by control signals from a central control station, in a way analogous to remotely controlled adjustable signposts, but in its interactions with the user equipment the beacon is autonomous, identifying which of its zones the user""s desired destination is in, and transmitting the appropriate xe2x80x9cturnxe2x80x9d information to get it to the next beacon on the way. The beacon has no knowledge of the rest of the route.
Each beacon has a detailed map of a small local area (the boundaries of which are, in fact, the adjacent beacons), and if the destination is in this area the beacon gives full information of the route to the destination. The system can therefore provide a user with directions to a destination defined more precisely than the beacon spacing. However, at the beginning of a journey, a user cannot use the system until he encounters a beacon.
This proposed system allows instant updating of the guidance instructions from a central control, and simpler in-vehicle equipment, but requires vast capital expenditure in roadside beacons.
A problem encountered with both the proposed systems described above is that it is difficult for them to provide alternative routings in response to congestion, either current or future, without the risk of creating worse problems on the alternative routes. Although predictions of regularly occurring congestion peaks are relatively simple to programme into the guidance information, and, at least in the beacon system, real-time updates on road congestion can also be fed to the programming of the beacons, the control system does not have any information of vehicle movements from which to predict future congestion. In any case, if the system is in use by a significant fraction of the vehicles, the system will tend to produce congestion on the diversionary routes.
A navigation information provides information to a mobile user dependant on the location of the mobile user is provided. The system includes a mobile communications system having a fixed part and one or more mobile part for communicating with the fixed part, the one or more mobile part including means for transmitting to the fixed part a request for guidance information and for receiving guidance information from the fixed part, and the fixed part including:
means for determining the location of a mobile part requesting guidance information,
means for generating guidance information according to the location of the mobile part, and
means for transmitting the guidance information so generated to the mobile part,
whereby information dependant on the location of the mobile unit can be transmitted to the mobile unit.
The exemplary navigation information system is one wherein the fixed part includes means for determining the location of the mobile part in relation to a geographical overlay comprising a plurality of overlay areas, and means for transmitting information associated with an overlay area which includes the location of the mobile part, whereby a mobile part within that overlay area receives information associated with that overlay area.
The exemplary navigation information system includes means for storing a digital representation of the geographical overlay, and means for modifying the stored representation such that the configurations of the overlay areas may be selected to meet changing requirements.
The exemplary navigation information system includes means for determining when a mobile part enters a predetermined overlay area, and means for transmitting a message to the mobile part, in response to the mobile part entering the predetermined overlay area.
The exemplary navigation information system includes means for determining when a mobile part enters a predetermined overlay area, and means for transmitting a message, to a user other than the said mobile part in response to the said mobile part entering the predetermined overlay area.
The exemplary navigation information system includes means to store a value associated with the mobile part, and means arranged to modify the stored value in response to the message.
The exemplary navigation information system, includes means for locating the position of the mobile part by radio location.
The exemplary navigation information system is one wherein the means for locating position comprises a satellite navigation system receiver and/or means for identifying the location of the mobile part in relation to elements of the fixed part of the communications system.
The exemplary navigation information system is one wherein the means for determining the location of the mobile part comprises means to interrogate a location-identifying means forming part of the mobile part.
The exemplary navigation information system is one wherein the fixed part has means to determine the approximate location of the mobile part, and wherein the location identifying means of the mobile part is arranged to respond to a location request from the interrogation means with a non-unique location signal which, in combination with the approximate location determined by the fixed part, determines a unique location.
The exemplary navigation information system is one wherein the mobile part has means for locating its position by dead reckoning.
The exemplary navigation information system is one wherein the fixed part includes means for generating and maintaining guidance data based on vehicle movement data derived from time information and position measurements of a plurality of the mobile parts and/or estimations of future locations of the mobile parts based on the guidance information previously transmitted to the mobile parts.
The exemplary navigation information system is one wherein the fixed part comprises means for transmitting to the mobile part an expected range of movement information and for receiving from the mobile part movement measurements outside the expected range, and the mobile part comprises means for measuring location and time to derive movement information, means to compare the movement information with the expected range received from a fixed part of the system, and means to automatically report to the fixed system movement measurements outside the expected range.
The exemplary navigation information system has a fixed part including means for storing guidance data, means for updating the stored guidance data, means for identifying mobile parts to which the updated data are applicable, and means for transmitting such data over the communications system to the mobile parts so identified.
The exemplary navigation information system is one wherein the mobile part includes guidance instruction means controllable by instructions contained in the guidance information transmitted from the fixed part over the communications link, whereby guidance instructions can be communicated to the user by means of the guidance instruction means.
The exemplary navigation information system is one wherein the fixed part has input means operable by a human operator to input guidance instruction requests to the fixed part.
The exemplary navigation information system provides information to one or more mobile user dependant on the location of the one or more mobile user, the system comprising:
means for determining the location of a mobile unit requesting guidance information,
means for generating guidance information according to the location of the mobile unit,
and a communications system for transmitting the guidance information so generated to the mobile unit,
whereby information dependant on the location of the mobile unit can be transmitted to the mobile unit.
The exemplary navigation information system includes means for determining the location of a mobile unit in relation to a geographical overlay comprising a plurality of overlay areas, and means for transmitting information associated with an overlay area which includes the location of the mobile unit, whereby a mobile part within that overlay area receives information associated with that overlay area.
The exemplary navigation information system includes means for storing a digital representation of the geographical overlay, and means for modifying the stored representation such that the configurations of the overlay areas may be selected to meet changing requirements.
The exemplary navigation information system includes means for determining when a mobile unit enters a predetermined overlay area, and means for transmitting a message to the mobile unit in response to the mobile unit entering the predetermined overlay area.
The exemplary navigation information system includes means for determining when a mobile unit enters a predetermined overlay area, and means for transmitting a message, to a user other than the said mobile unit, in response to the said mobile unit entering the predetermined overlay area.
The exemplary navigation information system includes means to store a value associated with the mobile unit, and means arranged to modify the stored value in response to the message.
The exemplary navigation information system is one wherein the means for determining the location of a mobile unit comprising means to interrogate a location-identifying means of a co-operating mobile unit to determine its position.
The exemplary navigation information system is one wherein the means for locating position comprises means for identifying the location of the mobile unit in relation to elements of the fixed part of the communications system.
The exemplary navigation information system is one wherein the means for locating position comprises means to determine the approximate location of the mobile unit, means to receive a non-unique location signal from the mobile unit, and means to combine the approximate location information with the non-unique location information to determine a unique location.
The exemplary navigation information system includes means for generating and maintaining guidance data based on vehicle movement data derived from time information and position measurements of a plurality of the mobile parts.
The exemplary navigation information system has means for transmitting to the mobile part an expected range of movement information, and for receiving from the mobile part movement measurements outside the expected range.
The exemplary navigation information system includes means for storing guidance data, means for updating the stored guidance data, means for identifying mobile units to which the updated data are applicable, and means for transmitting such data over the communications system to the mobile units so identified.
The exemplary navigation information system has input means operable by a human operator to input guidance instruction requests.
The exemplary mobile unit for a navigation information system includes means for receiving guidance instruction information over a communications link, and guidance instruction means controllable by the guidance instruction information received over the communications link, whereby guidance instructions can be communicated to the user by means of the guidance instruction means.
The exemplary mobile unit for a navigation information system includes means for measuring location and time to derive movement information, means to compare the movement information with an expected range received from a fixed part of the system, and means to automatically report to the fixed system movement measurements outside the expected range.
The exemplary method provides navigation information to mobile units of a mobile radio system dependant on the locations of the mobile units comprising the steps of storing navigation data in a fixed part, transmitting a request for navigation guidance from a mobile unit to the fixed part, determining the location of the mobile unit, generating guidance information on the basis of the stored data, location information and the request, and transmitting the guidance information from the fixed part to the mobile unit, whereby information relevant to the location of the mobile unit is transmitted to the mobile unit.
The exemplary method provides navigation information, wherein the location of the mobile unit is determined in relation to a geographical overlay comprising a plurality of overlay areas, generating information associated with an overlay area which includes the location of the mobile part, and transmitting the information associated with the relevant overlay area to the mobile part, whereby a mobile part within that overlay area receives information associated with that overlay area.
The exemplary method provides navigation information including the step of storing a digital representation of the geographical overlay, and modifying the stored representation such that the configurations of the overlay areas may be selected to meet changing requirements.
The exemplary method provides navigation information, comprising the further steps of determining when a mobile unit enters a predetermined overlay area, and transmitting a message to the mobile unit in response to the mobile unit entering the predetermined overlay area.
The exemplary method provides navigation information including the further steps of determining when a mobile unit enters a predetermined overlay area, and transmitting a message to a user other than the said mobile unit in response to the mobile unit entering the predetermined overlay area.
The exemplary method provides navigation information including the further step of modifying a stored value associated with the mobile unit in response to the message.
The exemplary method provides navigation information, wherein the position of the mobile unit is identified by a radio location method.
The exemplary method provides navigation information, wherein the position of the mobile unit is determined by means of a satellite navigation system and/or by identifying the location of the mobile part in relation to elements of the fixed part of the communications system.
The exemplary method provides navigation information, wherein the fixed unit interrogates the mobile unit to identify its location.
The exemplary method provides navigation information wherein the fixed part determines the approximate location of the mobile part, and wherein the mobile part responds to a location request from the interrogation means with a non-unique location signal which, in combination with the approximate location determined by the fixed part, determines a unique location.
The exemplary method provides navigation information, wherein the mobile unit identifies its position by dead reckoning.
The exemplary method provides navigation information, including the steps of generating and maintaining data based on vehicle movement data derived from time information and position measurements of a plurality of the mobile parts and/or estimations of future locations of the mobile parts based on the guidance information previously transmitted to the mobile parts.
The exemplary method provides navigation information wherein the fixed part transmits to the mobile part an expected range of movement information, and the mobile part measures location and time to derive movement information, compares the movement information with the expected range received from the fixed part of the system, and reports to the fixed system movement measurements outside the expected range.
The exemplary method provides navigation information including the further steps of the updating the stored data, identifying the mobile units to which the updated data are applicable, and transmitting such data over the communications system to said applicable mobile parts. A method of providing navigation information wherein the guidance information transmitted to the mobile unit controls guidance instruction means forming part of the mobile unit, whereby guidance instructions can be communicated to the user of the mobile unit.
This invention has advantages over both the prior art systems discussed above. Considerable improvements can be made over the prior on-board navigation system proposals, by putting the intelligence in the fixed part of the system. Firstly, there is no need to distribute maps or updates to subscribers because the data is held centrally. New roads can be added to the system at the instant they are opened. Total capital expenditure is minimised since all users share the same database. Moreover, the computing resources are used more efficiently, because an in-vehicle system spends most of its time inactive but a centralised system can be time-shared.
Moreover, in contrast to the prior art roadside beacon system, the invention can be implemented with little deployment of equipment in the field. thereby offering considerable economies in capital cost and maintenance, and allowing rapid installation and modification of the system to meet changing requirements.
Preferably the system includes means for determining the location of the mobile part in relation to a geographical overlay comprising a plurality of overlay areas, and means for transmitting information associated with an overlay area which includes the location of the mobile part, whereby a mobile part within that overlay area receives information associated with that overlay area. This allows information associated with a particular overlay area to be transmitted to any mobile units in that overlay area. The system may also comprise means for determining when a mobile par enters a predetermined overlay area, and means for transmitting a message, to a user other than the said mobile part, in response to the said mobile part entering the predetermined overlay area. For example, one overlay area may cover part of a road approaching a junction, and the message may be the appropriate instruction to the driver, as he approaches the junction, as to which way he should turn. Each individual overlay area therefore gives navigation instructions specific to that overlay area. The overlay areas may overlap, and may be of any size down to the practical minimum of the resolution of the location determination process. Large overlay areas are suitable for transmitting general information, whilst smaller areas can be used to target information to users in very precise locations, such as individual elements of a complicated road layout. The overlay areas may be delimited in two or three dimensions.
An advantage of this preferred arrangement over the fixed beacon systems is that the geographical overlay can be readily modified. Advantageously, the system includes means for storing a digital representation of the geographical overlay, and means for modifying the stored representation such that the configurations of the overlay areas may be selected to meet changing requirements. The overlay areas can be readily combined or subdivided, or their boundaries otherwise altered to meet changing circumstances without any modification to the hardware, simply by reconfiguring the geographical overlay defined in the central datacase. Moreover, unlike the prior art beacon system discussed above, there is no major cost in street furniture and supporting infrastructure, because existing cellular mobile communications systems may be used to transmit the instructions from a central database. If the driver enters an overlay area which is not on the route chosen by the system, an error message can be transmitted. Such messages may be transmitted to a user other than the mobile unit, for instance in order to monitor the whereabouts of valuable cargoes or of personnel working away from a base.
The geographical overlay may also be used to operate an access-control system, for example for site security or for levying tolls. In this arrangement, if a user enters an overlay area for which he does not have permission, an alert signal can be sent to a system controller, or to security staff on site who can intercept the interloper. Means may be provided (either in a fixed location or with the mobile user) to store a value associated with the mobile unit, and means arranged to modify the stared value in response to the messages transmitted in accordance with the location of the mobile unit, either to increment the value e.g. for subsequent billing, or to decrement the value e.g. in a prepaid stored-value device.
The fixed part may include means for storing map information or other data for use in providing information, herein referred to as guidance data, means for updating the stored guidance data, means for identifying mobile parts to which the updated data are applicable, and means for transmitting such data over the communications system to the mobile parts so identified. This allows information about changing traffic situations to be transmitted to all users who will be affected, without needing to broadcast the details to other users as would be the case with those prior art systems where updating is possible.
Although the information transmitted to the user is specific to the location, information about the user can be processed centrally. This allows short-term traffic predictions to be made. The guidance data transmitted to the mobile units can therefore be based on the position measurements of a plurality of the mobile parts. If the mobile parts are vehicles, these position measurements will identify the locations of roads, and an indication of their traffic density. As new roads are built or routes are diverted, traffic will move to the new routes. Measuring the position of the traffic will therefore result in the data being updated automatically. To reduce the volume of information transmitted, the fixed part may comprise means for transmitting to the mobile part an expected range of movement information and for receiving from the mobile part movement measurements outside the expected range, and the mobile part comprising means for measuring location and time to derive movement information, means to compare the movement information with the expected range received from a fixed part of the system, and means to automatically report to the fixed system movement measurements outside the expected range. In this way only exceptional traffic conditions are reported.
The fixed part may include means for generating and maintaining guidance data based on vehicle movement data derived from time information and position measurements of a plurality of the mobile parts and/or estimations of future locations of the mobile parts based on the guidance information previously transmitted to the mobile parts. Estimations of future locations of the mobile parts based on the guidance information previously transmitted to the mobile parts can be used to make estimates of future traffic situations.
The data stored in the data storage means may be updated, for example in response to changing traffic conditions, accidents, or highway maintenance. The system may include means for identifying the mobile units to which the updated data are applicable, and transmitting amended instructions over the communications system to said mobile parts. With knowledge of the journeys being planned by a large number of users, a better prediction of demand for particular roads (and hence of congestion on those roads) can be built up. This can be more stable than existing autonomous route-planning systems because the navigation system can take account of the journeys planned for other users.
Advantageously the invention can be implemented using a public cellular radio data service on an individual dial-up basis, providing a simple mechanism for billing and avoiding the need for a separate radio transmission system.
The means for determining the location of the mobile part may comprise means to interrogate a location-identifying means forming part of the mobile part operating for example by means of dead reckoning from a known start point, using an inertial navigation system or distance and direction measuring devices such as a compass and an odometer. Alternatively, the means for locating position may include means for identifying the location of the mobile part in relation to elements of the fixed part of the communications system. The location of the mobile part may be determined by a radio location system associated with the cellular radio system. In another alternative arrangement, a satellite navigation system may be used. In one preferred arrangement the fixed part has means to determine the approximate location of the mobile part, and the location identifying means of the mobile part is arranged to respond to a location request from the interrogation means with a non-unique location signal which, in combination with the approximate location determined by the fixed part, determines a unique location.
In a preferred arrangement, the fixed part and the mobile parts each have a satellite navigation system receiver, and the positions of the mobile parts as measured by the satellite navigation system are compared with those of the fixed part as measured by the satellite navigation system. The position of the fixed part can be known with great accuracy and provides a reference measurement which allows the position of the mobile part to be determined with greater accuracy than is possible by direct measurement using the satellite system alone.
Preferably the fixed part has one or more servers and means for allocating a server to a mobile part only when it requires service. In practice only a very small number of mobile units will require service at any given time, so this allows the computing resources of the fixed part to be used most efficiently, and the system can support many more mobile units in total than it has server capacity for. This is in contrast to the prior art system discussed above, in which each mobile unit requires a dedicated computer carried on board, which is only used for a fraction of the time. Moreover, all the servers can use a common road-use database, which can use the information on routes it has planned for mobile users to build a prediction of future road use status, such as likely congestion points, and build this into its guidance instruction process. For example the system can be arranged such that it does not direct more than a predetermined number of users to use a particular stretch of road at a particular time, and finds alternative routes for any users who would otherwise be directed along that road at that time. In this way the system can predict likely congestion points and take pre-emptive action.
The mobile part may include guidance instruction means controllable by instructions contained in the guidance information transmitted from the fixed part over the communications link, whereby guidance instructions can be communicated to the user by means of the guidance instruction means.
For some applications the vehicle may be controlled directly in response to the guidance information received over the communications link. However, for use on the public highway, it is preferable that the guidance information controls display means, which may be visual or audible or both, to indicate to a driver the direction to take.
The guidance instruction means may be programmable from the fixed part over the communications link, either automatically or by a human operator. The guidance instruction means may include a speech synthesiser, which may be located in the fixed part transmitting voice messages to the user over the communications system, or may be located in the mobile unit and controlled by data messages from the fixed part. The former arrangement allows the mobile unit to be simplified, whilst the latter arrangement requires a smaller signalling load.
In the described embodiment the mobile part is in a vehicle, but it may be a hand-held device for guiding a pedestrian. In one form, the mobile part may be a conventional mobile cellular radio unit. This allows a basic service to be provide to a user without the need for any dedicated equipment.